1. Field of the Invention
The present invention relates to protective apparel. In particular, the present invention relates to multilayered protective footgear that helps reduce the risk of injury to the wearer's feet and lower legs due to detonation of antipersonnel land mines.
2. Discussion of Background
One of the most unfortunate legacies of war is the lingering hazard posed by undetonated land mines (also termed antipersonnel mines). Perhaps as many as one third of the world's countries have a serious land mine problem resulting from past wars, internal conflicts, or terrorist activities. Land mines are cheap (costing as little as $3.00 per mine), easy to use, hard to detect, and, when detonated, capable of inflicting horrendous injuries on combatants and noncombatants alike. Many different types of land mines are available, including the following: blast mines, which burst on contact, are usually small and may injure only the unfortunate person who steps directly onto the mine; bounding mines rocket to a height of several feet above ground before blowing up, thus, frequently injure nearby bystanders as well; directional fragmenting mines can propel shrapnel as far as 200 meters. Information concerning the extent of the worldwide land mine problem is found in the following publications, the disclosures of which are incorporated herein by reference: "Land Mines: Horrors Begging For Solutions," Chemical & Engineering News, Mar. 10, 1997, pp. 14-22; "Minefields, Literal and Metaphoric," U.S. News & World Report, pp. 39-41, Feb. 3, 1997.
Land mines first came into widespread use during World War II. These early designs used relatively large amounts of explosive (on the order of 300 grams or more) and were designed to kill. Later, in the 1960's, land mines designed to maim and disfigure rather than to kill became available. These new designs typically use much smaller amounts of explosives (on the order of 100 grams) that are sufficient to kill only small children, but can severely maim an older child or an adult.
Land mines have become the antipersonnel weapon of choice for many rebel forces, particularly in places such as Afghanistan, Cambodia, Mozambique, and Zaire. Land mines are deployed whenever and wherever there is a possibility of inflicting injury to humans, combatants and noncombatants alike: in roads, in harbors, at airports, railroad stations, and other places where large numbers of people congregate, and even on farmland, making large areas of otherwise-productive land off-limits to civilians. Some estimates indicate that there are over one hundred million leftover, still-active land mines throughout the world, in over seventy countries; millions more are produced, sold, and used each year. Injuries due to land mine explosions kill or maim people--including children--at a rate of one victim every twenty minutes.
Because of the sheer numbers of casualties due to land mines, the health and medical services of many poor nations are strained to the breaking point. As noted above, present-day land mines maim their victims rather than kill them outright. Not only is the loss of a limb extremely painful to the victim and his or her family, but recovery is prolonged, and the cost of hospitalization and prostheses is high (amounting to more than a year's income for most victims).
Diplomatic efforts are presently underway to ban production and use of land mines. In the meantime, new, effective technologies for finding, defusing, and removing existing land mines are urgently needed. At present, land mines are typically cleared by tried-and-true methods that date back to World War II: mines-weepers carefully search areas suspected of containing mines with metal detectors and pointed sticks, and extract any mines found. Once unearthed, the mines are detonated or defused. Whatever the methods used to clear land of mines, the successful implementation of these methods depends on the availability of suitable protective apparel for those who carry out this dangerous but essential task.
Since most land mines are activated by pressure, the availability of suitable protective footgear is especially important for those working in an area that contains (or is suspected to contain) undetonated mines. Safety shoes with metal toe caps are well known in the art; indeed, many employers require that their employees wear safety shoes to help prevent on-the-job foot injuries. Many different designs for safety shoes are available, including that disclosed by Scherz in U.S. Pat. No. 4,366,629. Scherz describes a multi-layer safety boot with a sole and upper made of molded plastic material. The boot includes a metallic plate that extends the width and length of the sole, a box-shaped toe guard, and a rigid metatarsal guard.
Safety devices for protecting the feet and lower legs of combat troops and civilians from the effects of blast and fragmentation associated with the detonation of mines (including small antipersonnel land mines) are also known. By way of example, Ringler, et al. (U.S. Pat. No. 4,611,411) disclose a mine-field shoe consisting of a rigid tread made of aluminum with an inflatable, multi-compartment air cushion. The device is attached to the user's boot by straps.
Other types of protective foot-gear are disclosed by Jordan (U.S. Pat. No. 3,516,181), Lewis, Jr., et al. (U.S. Pat. No. 3,243,898), Barron (U.S. Pat. No. 3,061,951), and Krohn, et al. (U.S. Pat. No. 2,720,714). These devices make use of a variety of materials, including foam rubber, fiberglass, rubber sheeting, and building materials such as Dylite.RTM. and Celotex.RTM. . Jordan's device consists of an armored wedge supported by a rectangular strip of rubber. The wedge is filled with an acoustic filler material (such as Dylite.RTM.) which dampens and attenuates shocks transmitted through the sides of the wedge. Lewis, Jr., et al. show a device that includes a plastic platform and a wedge made of metal or laminated fiberglass. The wedge may be reinforced by a fiberglass or Teflon.RTM. backing, and is filled with a blast-attenuating acoustic filler material such as Celotex.RTM. or balsa wood. It may be mounted in a plastic hull or a balsa-wood block. Barron's blast attenuating footwear includes a layer of non-elastic honeycomb material (made of paper, textile, aluminum, plastic, or rubber) and a rubber outsole. Krohn, et al. provide a protective footpad having a plurality of layers, including layers of natural and synthetic foam rubber, rubberized waterproof fabric, and metal. Adjustable metal heel and toe plates help protect the user's feet from blast injuries. All of these devices are strapped to the user's shoes or boots for use.
Presently-available designs for protective footgear tend to be cumbersome to wear, of relatively complex construction, and expensive to manufacture. Designs that provide reasonably effective protection typically cost hundreds of dollars per pair, and are simply not affordable in those parts of the world where the need for protective footgear is greatest; more affordable designs offer the user little protection against modern antipersonnel mines. There is a need for protective footgear which is simple and easy to make, cost-effective, and provides its wearer with a significant degree of protection against foot and lower leg injury due to land mine explosions.